In vehicle design, meeting noise and vibration requirements is increasingly important. In meeting both requirements, the design, placement, and operation of engine components in the engine compartment of a vehicle plays a significant role.
Generally speaking, components disposed in an engine compartment of a vehicle are subject to vibrational forces created by the engine and movement of a vehicle. For components such as hydraulic power steering hoses and the like, additional vibrational forces are created due to the pressure pulses and movement of hydraulic fluid within the system. Such additional vibrational forces can cause components to vibrate, rattle or squeak, thereby increasing passenger compartment noise and reducing occupant comfort.
In an effort to improve occupant comfort and reduce passenger and engine compartment noise, conventional damping systems have attempted to offset hydraulic noise through the use of tuning cables and restrictors. Tuning cables generally extend the length of a hydraulic hose and are specific to a particular hydraulic system. Specifically, conventional systems commonly include an elongate, wire wound cable, formed integrally with, or attached to, a hydraulic line and are operable to obviate the noise created by pressure pulses and/or moving fluid within the line. In essence, tuning cables serve to absorb the vibrational force created by the pressure pulses and moving hydraulic fluid and reduce the associated noise. While such systems effectively absorb vibrational forces created by pressure pulses and fluid movement, they fail to offset the additional vibrational forces caused by structural vibration.
Structural vibration is generally initiated by components disposed within an engine compartment of a vehicle. Such vibration generally transmits to a passenger compartment of the vehicle via systems that extend between the engine and passenger compartments. In one example, a hydraulic power steering system includes at least one hydraulic line which is attached at a first end to the engine compartment of a vehicle and at a second end at the hydraulic steering system. As previously discussed, an engine compartment of a vehicle experiences vibrational forces due to the movement of the vehicle and operation of the engine. In this regard, the first end of the hydraulic line, which is attached at the engine compartment, is subject to vibrational forces. As can be appreciated, the vibrational forces imparted on the first end of the hydraulic line tends to transfer from the attachment point to the line itself. Such structural vibration can cause the line to transmit vibration into the passenger compartment of the vehicle and create noise.
Therefore, a mass damper that is operable to absorb vibrational forces caused by both structural and fluid forces is desirable in the industry. Further, a mass damper that is capable of being tuned for different systems, thereby being easily transferable between different fluid lines and different systems, is desirable in the industry.